I think this is largely just "location, location, location." For some reason there is this innate draw to major population centers of a certain "type" and it's forms a self reinforcing feedback loop. I think the term for it is network effect.

What I think is silly is people fall for it every time. Do a large number of successful startups come out of SF and NYC? Yes. Does everyone who moves there get to participate in one? No.

Even if you are a super-genius, with good looks, a good sales pitch, and ooze charisma, you still may not make it.

Yes, ambitious people go to these tech "Meccas" but I don't think it really increases any one individual person's chance of making it big.

I think the saddest part of it all, is even whilst living in the most connected age that has ever existed, we still find location so important.